A damning UN report has accused Myanmar’s military of genocide against the Rohingya in Rakhine state, and alleged that the army were responsible for war crimes and crimes against humanity against minorities across the country.

A fact-finding mission on Myanmar compiled conclusive evidence that what its military, known as the Tatmadaw, had carried out “undoubtedly amounted to the gravest crimes under international law” in Rakhine, home to the Muslim Rohingya, but also in Kachin and Shan states which are riven by internal conflicts.

The UN investigators were denied access to Myanmar by the government but interviewed many who had fled the country. They found that the military were “killing indiscriminately, gang raping women, assaulting children and burning entire villages” in Rakhine, Shan and Kachin. They also carried out murders, imprisonments, enforced disappearances, torture, rapes and used sexual slavery and other forms of sexual violence, persecution and enslavement – all of which constitute crimes against humanity.

In northern Rakhine, the mission also found evidence of mass extermination and deportation, both defined as crimes against humanity by the UN.

The mission, prompted by the UN security council visit in March, called for an investigation into the military over the genocide in Rakhine. The campaign of violence against the Rohingya began exactly a year ago. An estimated 25,000 have been killed and 700,000 have fled over the border to Bangladesh.

Laying out the legal argument for genocide to have taken place, the UN report stated that “the crimes in Rakhine state, and the manner in which they were perpetrated, are similar in nature, gravity and scope to those that have allowed genocidal intent to be established in other contexts”.

Specific individuals were singled out for investigation and prosecution for genocide and crimes against humanity, namely Min Aung Hlaing, commander-in-chief of the Tatmadaw, who has openly stated his intention to solve “the long-standing Bengali problem”.

“There is sufficient information to warrant the investigation and prosecution of senior officials in the Tatmadaw chain of command, so that a competent court can determine their liability for genocide in relation to the situation in Rakhine state,” stated the report.

The mission also backed calls for Myanmar to be investigated by the international criminal court (ICC), though as Myanmar is not a signatory to the Rome statute, and therefore not under the jurisdiction of the court, ICC prosecutors are deliberating over whether they can investigate the violence in Rakhine.

The UN report is sure to rile Myanmar’s military and government, who have denied that genocide occurred in Rakhine and claimed that the Rohingya – who they regularly refer to as “illegal Bengali immigrants” – instigated the violence by attacking the security forces and then burned their own villages to the ground. Both the military and the civilian government, led by Nobel peace prize winner Aung San Suu Kyi, have stated that the military’s actions were an appropriate response to “terrorists”.

The Tatmadaw’s own investigation, widely considered a farce, cleared the military of all wrongdoing and the head of Aung San Suu Kyi’s newly established inquiry into Rakhine recently stated that there will be no “finger-pointing, blaming, to say ‘you’re accountable’.”

The UN report criticised Aung San Suu Kyi’s passive role over the past year. “[She] has not used her de facto position as head of government, nor her moral authority, to stem or prevent the unfolding events in Rakhine state,” it said.

The UN stated that, with Myanmar’s repeated failure to admit that genocide had taken place and with the legal impunity given to the military, it now fell to the international community to hold those responsible to account.

“Theresa May must now support the referral of Burma to the international criminal court,” said Mark Farmaner, Director of Burma Campaign UK in response to the UN mission. “By not supporting referring Burma to the international criminal court, Theresa May is in effect protecting Min Aung Hlaing and his military from attempts to bring them to justice.”